Different drivers have different driving styles, and the driving styles may affect, for example, fuel economy. An aggressive driver may accelerate forward more quickly than a less aggressive driver, and may brake (creating negative acceleration) harder and faster than a less aggressive driver. A gentler, efficiency minded, or eco-friendly driver may accelerate forward more slowly or softly than an aggressive driver, and may brake more gently or gradually.
It would be desirable to provide feedback to drivers, or other systems regarding driving style, relative to other drivers. It would be desirable to provide such information using hardware such as sensors already existing in a vehicle.